Temp of Oil as shown on the MFD

[Diesel_vert]

I wonder what temp would be too high...

Most modern cars that I've seen with oil temperature gauges allow the oil temperature to reach 140-150°C before the vehicle warns you of a high oil temperature.

We know there's no inherent danger in revving the engine, or even cruising at, very high RPMs as it's part of the design brief - so long as you don't go beyond the redline.

Similarly, there is no inherent danger in allowing oil temperatures to reach very high because it's part of the design brief (for both the engine and the oil) - so long as you don't exceed the temperature warning threshold or skimp on oil.

Obviously, if the engine is likely to experience high oil temperatures for an extended period of time (frequent towing, track days, racing, etc) then it would be smart to deal with that by fitting axillary oil coolers and such.

However, in the same way that keeping the engine revs down would aid in its longevity, so will keeping the oil temperature down (but not too low, as you want it to be hot enough to deal with moisture, fuel dilution, etc - short trips are much more likely to kill the engine rather than high oil temps).

... and worth being concerned about?

Not unless something is malfunctioning on the engine.

Storm in a teacup.

[zei20t]

modern engines run much higher than 'older' ones. my last few cars have had water temps 90-100 and oil temps around the same. except when I give it the boot

[Mysticality]

The Water temp gauge on the dashboard is very quick to act... When the water temp is 90 and the oil temp is 50, the actual water temp is around 70^C.

The highest oil temp I've seen my diesel cruise at is 105, the lowest cruise (more than 10min) is 89. Highest I've ever seen it at is 112, but that was after some extreme driving up a huge hill.

I have water temps from 89-94^C. (OBD-II scanner)

Usually the water is at 89 and the oil is at 94-100.

[Martin]

modern engines run much higher than 'older' ones. my last few cars have had water temps 90-100

Agreed, modern engines are putting out a lot more power per litre which results in a lot more heat
After a journey on a hot day you can pop the bonnet and find it's unconfortable to leave your hand on the shock tower

The water should stay around 90 - can't have it reaching 100

[zei20t]

of course you can have it over 100. the system is under pressure so its not going to boil. also additives will help prevent boiling.

ive had my old car up to 118, but turns out there was a leak.

hotter engines means cleaner burns and less emissions.......

[brad]

of course you can have it over 100. the system is under pressure so its not going to boil. also additives will help prevent boiling.
.

For every 10kPa of pressurisation it raises the boiling temp of water by 2c? Typical pressurisation is ~120kPa?

With the correct ratio of coolant the boiling point would be ~130c?

This is why a radiator that doesn't appear to be boiling/overheated send out a huge geyser if you are silly enough to remove the cap when hot - release of pressure which then causes the water to boil

[Martin]

Interesting guys - makes sense

I've never encountered high water temperatures
Last week it was 45 degrees on Tuesday, my water temp was steady on ~92 deg

[zei20t]

put the AC, load the car up with the family and all associated crap and go sit in traffic

[Mysticality]

put the AC, load the car up with the family and all associated crap and go sit in traffic

Minus family, plus gear in the back seat and thats what I was doing.
Must be when I hit 94.

It would seem that the Octy has an amazing amount of cooling power, but hardly uses any of it.

[zei20t]

probably because its engineered to work from -20 - +50 without issues

I think there is a large volume of coolant in the system, and oil also.